If he's like me then it isn't a matter of storage capacity - having multiple drives is for redundancy. I have 8 hard drives inside 3 PC's in my computer room alone.

Mhh, I come to 12 drives... but unlike many others, I have huge storage needs apparently. Even if there'd be 4TB drives, I would probably only consider upgrading once I am convinced they are not a fad and nothing ever follows up, If we got just by capacity, I'd love to get 2x60TB drives and just throw everything else out. (out of my PC, that is ,p) not out of my general storage.